Content transmitter, content transmitting method and program

ABSTRACT

A content transmitter transmits content over a network, and includes: an input section configured to obtain the content, a first kind of information indicating, based on at least one of the destination and transmission method of the content, whether transmission of the content is permitted or not, and a second kind of information specifying the destination of the content; a control section configured to determine, by reference to the first and second kinds of information, whether or not to transmit the content to the destination and rewrites the first kind of information; and an output section configured to output the content and the first kind of information that has been rewritten.

BACKGROUND

1. Technical Field

The present disclosure relates to a technique for transmitting contentover a network.

2. Description of the Related Art

As computer networks have been rapidly developing these days, it hasbecome very easy to transmit some content such as a video clip or anaudio file from one computer terminal to another.

However, as such content to transmit often includes sensitiveconfidential or personal information, there is an increasing demand forsafe and secure telecommunications controls that can eliminate the riskof information leaking. Thus, in response to such a demand, variousaccess control systems and methods have been proposed to realize safeand secure telecommunications controls.

For example, Japanese Laid-Open Patent Publication No. 2001-297063discloses that an access control may be carried out using an ID and apassword assigned to each individual user when he or she attempts totransmit some content. On the other hand, Japanese Laid-Open PatentPublication No. 2000-354067 discloses a technique for performing anaccess control by making a router, which is located between a server anda group of clients, decide whether to relay or discard the given contenton a content basis and on a client basis. Furthermore, PCT InternationalApplication Japanese National-Phase Patent Publication No. 2005-529519discloses a technique for performing an access control by providing anauthentication field, which indicates either a mode that permitsdistribution to outside of a network or a mode that prohibitsdistribution to outside of the network, for content data.

SUMMARY

According to these techniques, however, the access control cannot becarried out flexibly enough depending on the destination or the mode oftransmission, and safety of telecommunications cannot always be ensured.

One non-limiting, and exemplary embodiment provides a contenttransmission technique which contributes to realizing safe and securetelecommunications by carrying out an access control more flexibly thanin the related art while attempting to transmit content over a network.

In one general aspect, a content transmitter as an embodiment of thepresent disclosure transmits content over a network, and includes: aninput section configured to obtain the content, a first kind ofinformation indicating, based on at least one of the destination andtransmission method of the content, whether transmission of the contentis permitted or not, and a second kind of information specifying thedestination of the content; a control section configured to determine,by reference to the first and second kinds of information, whether ornot to transmit the content to the destination and rewrites the firstkind of information; and an output section configured to output thecontent and the first kind of information that has been rewritten.

According to the above aspect, the access control can be carried outmore flexibly than in the related art and content can be transmittedsafely and securely over a network.

These general and specific aspects may be implemented using a system, amethod, and a computer program, and any combination of systems, methods,and computer programs.

Additional benefits and advantages of the disclosed embodiments will beapparent from the specification and Figures. The benefits and/oradvantages may be individually provided by the various embodiments andfeatures of the specification and drawings disclosure, and need not allbe provided in order to obtain one or more of the same.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a general configuration for acontent transmitter as an embodiment.

FIG. 2 is a flowchart showing generally how the content transmitteroperates according to that embodiment.

FIG. 3 is a schematic representation illustrating an overallconfiguration for a network according to a first embodiment.

FIG. 4 is a block diagram illustrating a configuration for a contenttransmitter according to the first embodiment.

FIG. 5 is a table showing an example of transmission control informationaccording to the first embodiment.

FIG. 6 is a flowchart showing an exemplary procedure of setting thetransmission control information according to the first embodiment.

FIG. 7 is a flowchart outlining the procedure of transmission controlinformation rewriting processing according to the first embodiment.

FIG. 8 is a flowchart showing the procedure of determining transmissioncontrol information that has been rewritten in a situation where contentis transmitted to the same sub-net according to the first embodiment.

FIG. 9 is a flowchart showing the procedure of determining transmissioncontrol information that has been rewritten in a situation where contentis transmitted different sub-nets according to the first embodiment.

DETAILED DESCRIPTION

Hereinafter, embodiments will be described in detail with reference tothe accompanying drawings as needed. It should be noted that thedescription thereof will be sometimes omitted unless it is absolutelynecessary to go into details. For example, description of a matter thatis already well known in the related art will be sometimes omitted, sowill be a redundant description of substantially the same configuration.This is done solely for the purpose of avoiding redundancies and makingthe following description of embodiments as easily understandable forthose skilled in the art as possible.

It should be noted that the present inventors provide the accompanyingdrawings and the following description to help those skilled in the artunderstand the present disclosure fully. And it is not intended that thesubject matter defined by the appended claims is limited by thosedrawings or the description.

Before specific embodiments are described, the basic configuration andoperation of an embodiment of the present disclosure will be described.

FIG. 1 is a block diagram illustrating a configuration for a contenttransmitter 101 as an embodiment. The content transmitter 101 cantransmit content over a network and includes an input section 14 whichobtains content and other kinds of information, a control section 110which controls transmission of the content in accordance with theinformation collected, and an output section 112 which outputs thecontent to an external device. The network that is supposed to be usedin this embodiment is an IPv4 (Internet Protocol Version 4) based TCP/IPnetwork but may also be an IPv6 (Internet Protocol Version 6) basednetwork or any other kind of network.

The input section 114 obtains the content to transmit, a first kind ofinformation indicating, based on at least one of the destination andtransmission method of the content, whether transmission of the contentis permitted or not (which will be sometimes referred to herein as“transmission control information”), and a second kind of informationspecifying the destination of the content (which will be sometimesreferred to herein as “destination information”). In this description,the “content” refers herein to electronic data such as video, audio ordocument, the “destination” refers herein to either a device (host) or anetwork (including a sub-net) to be identified by the address of thedestination to which the content is to be transmitted, for example, andthe “transmission method” refers herein to the mode of transmission suchas unicast, multicast or broadcast in an IPv4 network or the mode oftransmission such as unicast, multicast, or anycast in an IPv6 network.By using the transmission control information that is associated withthe content to transmit, the control can be carried out so thattransmission is permitted to only particular destinations or that only aparticular transmission method is permitted. Although the input section114 is illustrated as a single block in FIG. 1, the input section 114may also be made up of multiple sections that obtain the content, thetransmission control information and the destination information,respectively. Optionally, the content and the transmission controlinformation may be managed as a single aggregated file by adding thetransmission control information to the header of content data, forexample.

By reference to the transmission control information and destinationinformation obtained by the input section 114, the control section 110determines whether or not to transmit the content to the destination andrewrites the transmission control information as needed by reference tothe transmission control information and the destination informationwhen transmitting the content. The decision whether or not to transmitthe content is made based on the contents of the transmission controlinformation, information about the network (or sub-net) of thedestination identified by the destination information, and informationabout the transmission method. The transmission control information isrewritten in accordance with a predetermined transmission control policyso as to conform to the contents of the current transmission controlinformation. It will be described in detail later exactly how thecontrol section 110 performs its control operation.

The output section 112 may be a terminal through which the content andthe transmission control information that has been rewritten are outputto the destination. In this manner, the content and transmission controlinformation are transmitted to the destination over the network.

FIG. 2 is a flowchart showing generally how this content transmitter 101operates. First of all, in Step S101, the input section 114 obtains thecontent and the transmission control information from an external devicesuch as another information processor or storage device. Next, in StepS102, the input section 114 obtains the destination information, whichmay be entered by the user, for example. Optionally, these processingsteps S101 and S102 may be performed in reverse order or in parallelwith each other.

Next, in Step S103, the control section 110 determines, by reference tothe transmission control information and the destination information,whether or not to transmit the content to the destination specified. Ifthe control section 110 decides that the content not be transmitted, theprocess ends at this point in time. Or a signal indicating that thecontent will not be transmitted may be output to an external device. Onthe other hand, if the control section 110 has decided that the contentbe transmitted, then the control section 110 determines, in the nextprocessing step S104, whether or not the transmission controlinformation should be rewritten. This decision is made by reference tothe transmission control information and the destination information asdescribed above. If the control section 110 has decided that thetransmission control information be rewritten, the control section 110rewrites the transmission control information in Step S105 based on theoriginal transmission control information and the destinationinformation. It will be described later specifically how to rewrite thetransmission control information. On the other hand, if the controlsection 110 has decided in Step S104 that the transmission controlinformation not be rewritten, then this processing step S105 is skipped.Next, in Step S106, the output section 112 outputs the content and thetransmission control information to an external device.

By performing these processing steps, the transmission controlinformation that has been sent to the destination is appropriatelyrewritten by the control section 110, and therefore, it is possible toprevent the third party from getting the content illegally. In thismanner, the access control can be carried out more flexibly than in therelated art and safe and secure communications are realized.

According to the traditional access control using an ID and a password,safety from secondary transmission cannot be ensured for the client thathas received content. For example, if the ID and the password have notbeen set appropriately by the client who has received the content, thensecondary transmission to an unauthorized client may also be permitted.On the other hand, according to the access control in which the routerdecides to either relay or discard the given content, every content tobe relayed and every authorized client should be registered with everyrouter on the route, which is troublesome in the case of a large scalenetwork. Furthermore, according to the access control that provides thecontent with an authentication field, indicating whether content may ormay not be distributed to a user outside of the network, content thatshould not be distributed to anyone outside of the network never goesout of the network. On the other hand, content that may be distributedto anyone outside of the network will go out of the network freely. Thatis why it is difficult to carry out the access control flexibly.

However, according to the technique of the present disclosure, such aproblem can be overcome. Hereinafter, embodiments of the presentdisclosure will be described more specifically.

Embodiment 1

A content transmitter as a first embodiment belongs to a TCP/IP network,retrieves content with transmission control information for use tocontrol transmission from an external storage device, rewrites thetransmission control information according to the destination, and thenoutputs the content to the destination IP address. In this case, thetransmission control information is rewritten in accordance with thecontent source's transmission control policy.

1-1. Configuration

FIG. 3 is a schematic representation illustrating an overallconfiguration for a network that uses content transmitters 101 accordingthis embodiment. This embodiment is supposed to be used in a situationwhere broadcasters such as TV stations communicate video content betweentheir business locations. Sites 1, 2 and 3 shown in FIG. 1 may be threedifferent departments in the same broadcaster, for example. At each ofthose sites, provided are one or more content transmitters 101 and anexternal storage device 102. The content transmitters 101 at therespective sites are connected together so as to communicate with eachother in accordance with the TCP/IP protocol over the communicationsnetwork 50. In this example, those sites are supposed to belong tomutually different sub-nets. Each content transmitter 101 at each sitecan transmit content to another content transmitter 101 belonging to thesame or different sub-net or other computers. The content transmitter101 may be a personal computer (PC) installed in each department or acamcorder for use to create video content.

FIG. 4 is a block diagram illustrating a configuration for a contenttransmitter according to this embodiment. The content transmitter 101includes an input section 114 which obtains content and other necessaryinformation, a control section 110 which controls transmission of thecontent, and an output section 103 which outputs the content to anexternal device.

The input section 114 is suitably implemented as a combination of a datainput terminal and a keyboard or any other user interface which allowsthe user to enter his or her instruction. For example, the input section114 includes a terminal through which the content data stored in theexternal storage device 102 is obtained, a terminal through whichinformation (such as an IP address or a domain name) indicating thedestination specified by the user is obtained, and a user interface suchas a keyboard and an input screen.

The control section 110 includes a transmission control informationobtaining section 104 which gets transmission control information fromthe content data received, a destination information obtaining section106 which gets destination information that has been entered by theuser, a transmission decision section 105 which decides, by reference tothe transmission control information and the destination information,whether or not to transmit the content, and a transmission controlinformation rewriting section 107 which rewrites the transmissioncontrol information if decision has been made that the content betransmitted. These functional sections are suitably implemented as acombination of a processor such as a digital signal processor (DSP) anda central processing unit (CPU) and a program stored on a storage medium(not shown). Alternatively, they may also be implemented as dedicatedintegrated circuits that are designed so as to perform the respectivekinds of processing described above.

The output section 112 includes output terminals 103 and 108, throughwhich the content (including the transmission control information)supplied from the control section 110 is transmitted to its destinationover the network. Optionally, the output terminal 108 connected to thetransmission decision section 105 and the output terminal 103 connectedto the transmission control information rewriting section 107 may be thesame output terminal.

In addition to these components, the content transmitter 101 may furtherinclude a graphic controller which controls what is presented on thedisplay, a network controller which controls communications, a storagemedium, a power supply and other elements. Those elements may be anappropriate combination of known elements.

1-2. Operation

The content transmitter 101 retrieves content including the transmissioncontrol information from the external storage device 102 and determines,by reference to the transmission control information, whether thecontent may be transmitted or not. If the answer is YES, thetransmission decision section 105 outputs the content to the destinationIP address through the output terminal 103. Otherwise, the transmissiondecision section 105 outputs a transmission refusal signal through theoutput terminal 108. Alternatively, the transmission decision section105 may output no signals instead of outputting the transmission refusalsignal. The transmission control information is used to controltransmission of content. With the transmission control information, eachindividual content can be marked “transmission permitted” or“transmission prohibited” with respect to each of various castingmethods including the unicast for transmitting content to only a singledevice, the multicast for transmitting content to a group of devices,and the broadcast for transmitting content to every device belonging tothe same network (or the same sub-net). In addition, each individualcontent can be marked “transmission permitted” or “transmissionprohibited” depending on whether the source and destination of thecontent belong to the same sub-net.

FIG. 5 shows an example of the transmission control information. Asshown in FIG. 5, each piece of transmission control informationaccording to this embodiment is six-bit information. In FIG. 5, shownare some examples of the transmission control information, which arerepresented as hexadecimal numbers, and their respective bit values.Each of those bit values of the transmission control informationindicates whether transmission is permitted or not in those variousmodes of transmission. Specifically, the first three bits of thetransmission control information are pieces of information about asituation where content is supposed to be transmitted within the samesub-net and indicate whether transmission is permitted or not in thecases of unicast, multicast and broadcast, respectively. On the otherhand, the last three bits of the transmission control information arepieces of information about a situation where content is supposed to betransmitted to a different sub-net and indicate whether transmission ispermitted or not in the cases of unicast, multicast and broadcast,respectively. As for any of these bits, “1 (one)” indicates thattransmission is permitted and “0 (zero)” indicates that transmission isprohibited.

In the table shown in FIG. 5, “0x” indicates that this is a hexadecimalnumber. For example, if only unicast within the same sub-net ispermitted and transmission in any other mode is prohibited, then onlythe first bit becomes “1” and the other bits become “0”, and therefore,the transmission control information is represented as “0x20” in thatcase. On the other hand, if only broadcast to a different sub-net isprohibited and transmission in any other mode is permitted, then onlythe last bit becomes “0” and the other bits become “1”, and therefore,the transmission control information is represented as “0x3e” in thatcase. The transmission control information could be set to be differentvalues from the ones shown in FIG. 5.

FIG. 6 is a flowchart showing an exemplary procedure of setting thetransmission control information. The transmission control informationmay be set by a device (such as a camcorder or a PC) that has generatedthe content. Alternatively, after the content has been created, thetransmission control information may be changed in accordance with theuser's instruction.

In generating the transmission control information, first of all, inStep S301, the transmission control information is set to be “0”. Next,in Step S302, a decision is made whether broadcast to a differentsub-net is permitted or not. If the answer is YES, the process advancesto Step S303, in which “0x01” (i.e., 000001) is added to thetransmission control information. Otherwise, this processing step S303is skipped. Next, in Step S304, a decision is made whether multicast toa different sub-net is permitted or not. If the answer is YES, theprocess advances to Step S305, in which “0x02” (i.e., 000010) is addedto the transmission control information. Otherwise, this processing stepS305 is skipped. Next, in Step S306, a decision is made whether unicastto a different sub-net is permitted or not. If the answer is YES, theprocess advances to Step S307, in which “0x04” (i.e., 000100) is addedto the transmission control information. Otherwise, this processing stepS307 is skipped. By performing these processing steps, settings can bemade as to whether broadcast, multicast and unicast transmissions to adifferent sub-net are permitted or not.

Subsequently, settings are sequentially made as to whether broadcast,multicast and unicast transmissions to the same sub-net are permitted ornot. Specifically, in Step S308, a decision is made whether broadcast tothe same sub-net is permitted or not. If the answer is YES, the processadvances to Step S309, in which “0x08” (i.e., 001000) is added to thetransmission control information. Next, in Step S310, a decision is madewhether multicast to the same sub-net is permitted or not. If the answeris YES, the process advances to Step S311, in which “0x10” (i.e.,010000) is added to the transmission control information. Subsequently,in Step S312, a decision is made whether unicast to the same sub-net ispermitted or not. If the answer is YES, the process advances to StepS313, in which “0x20” (i.e., 1000000) is added to the transmissioncontrol information. By performing these processing steps, thetransmission control information can be defined.

Next, it will be described how this content transmitter operates whenthe control section 101 transmits content.

The transmission control information obtaining section 104 gets thetransmission control information from the content retrieved and outputsit to the transmission decision section 105 and the transmission controlinformation rewriting section 107. The destination information obtainingsection 106 outputs the destination IP address of the content that hasbeen provided by an external device to the transmission decision section105 and the transmission control information rewriting section 107. Thetransmission decision section 105 decides, based on the transmissioncontrol information and destination IP address provided, whether thegiven content may be transmitted or not. If the answer is YES, thetransmission decision section 105 outputs the given content. Otherwise,the transmission decision section 105 outputs a transmission refusalsignal through the output terminal 108. Optionally, the transmissiondecision section 105 may output no signals at all, instead of outputtingthe transmission refusal signal, as described above.

Based on the transmission control information and destination IP addressprovided, the transmission control information rewriting section 107rewrites the transmission control information included in the givencontent and outputs the rewritten transmission control information. Inthis processing step, a different transmission control policy is appliedaccording to the transmission mode of the content.

FIG. 7 is a flowchart outlining the processing to be carried out by thetransmission control information rewriting section 107. First of all,the transmission control information rewriting section 107 getstransmission control information and destination IP address information(in Step S401). Next, by reference to the destination IP address, thetransmission control information rewriting section 107 determineswhether or not the content transmitter 101 that is the source of thecontent and the device on the receiving end belong to the same sub-net(in Step S402). If the decision is made that they belong to the samesub-net, the transmission control information rewriting section 107rewrites the transmission control information in accordance with a firsttransmission control policy (in Step S403). On the other hand, if thedecision is made that the device on the receiving end and the contenttransmitter 101 belong to mutually different sub-nets, then thetransmission control information rewriting section 107 rewrites thetransmission control information in accordance with a secondtransmission control policy (in Step S404). After that, the transmissioncontrol information rewriting section 107 outputs the transmissioncontrol information (in Step S405).

FIG. 8 is a flowchart showing how the transmission control informationis rewritten in the processing step S403 in accordance with the firsttransmission control policy. Under this transmission control policy, thetransmission control information that has been rewritten with respect totwo different sub-nets inherits the previous transmission controlinformation with respect to those different sub-nets. On the other hand,the transmission control information that has been rewritten withrespect to the same sub-net is determined depending on whether thecontent to transmit is unicast-only content or else. If the content totransmit is unicast-only content with respect to the same sub-net (i.e.,if the first three bits of the transmission control information is“100”), no secondary transmission to the same sub-net is permitted.Thus, the first bit indicating whether or not unicast transmission tothe same sub-net is permitted is rewritten from “1” into “0”. Thismeasure is taken following the policy that content that may only beunicast to the same sub-net may not be transmitted to any device otherthan the target device. As for any other kind of content, however, theprevious transmission control information with respect to the samesub-net is inherited. This measure is taken because content that may bemulticast or broadcast to the same sub-net should maintain that stateeven after the transmission.

It will be described specifically in what procedure the transmissioncontrol information rewriting processing shown in FIG. 8 is carried out.First of all, the transmission control information rewriting section 107defines the logical product of the current transmission controlinformation and a bit string “0x07” (i.e., “000111”) to be newtransmission control information (in Step S501). As a result, the upperthree bits are set to be “000” and the lower three bits remain the sameas the previous information. Next, the transmission control informationrewriting section 107 determines whether broadcast to the same sub-netas described in the previous transmission control information ispermitted or not (in Step S502). If the decision is made that broadcastto the same sub-net is permitted, the process advances to Step S503, inwhich “0x08” (i.e., “001000”) is added to the new transmission controlinformation. After that, by performing the processing steps S504 throughS507, S510 and S511, the contents of the previous transmission controlinformation are maintained. On the other hand, if the decision is madein Step S502 that broadcast to the same sub-net is prohibited, then thetransmission control information rewriting section 107 determines inStep S508 whether or not multicast to the same sub-net is permitted. Ifthe answer is NO, then the process ends, because unicast to the samesub-net should be prohibited, no matter whether unicast to the samesub-net is permitted or not as per the previous transmission controlinformation. On the other hand, if the answer to the query of theprocessing step S508 is YES, then the series of processing steps S509through S511 are carried out and the same contents as the previous onesare maintained.

FIG. 9 is a flowchart showing how the transmission control informationis rewritten in the processing step S403 shown in FIG. 7 in accordancewith the second transmission control policy. Under this transmissioncontrol policy, no secondary transmission from the destination of thecontent to a different sub-net is permitted. Also, if the device on thereceiving end of the content makes a secondary transmission to the samesub-net that the destination of the content belongs to, then thetransmission control information is determined depending on whether thecontent to transmit is unicast-only content or else. If the content totransmit is unicast-only content, no secondary transmission ispermitted. Otherwise, the contents of the transmission controlinformation are set to be the same as those of the transmission controlinformation to different sub-nets at the source of the content.

It will be described specifically in what procedure the transmissioncontrol information rewriting processing shown in FIG. 9 is carried out.First of all, the transmission control information rewriting section 107sets the transmission control information to be zero (i.e., “000000”) inStep S601. Next, the transmission control information rewriting section107 determines whether broadcast to different sub-nets as described inthe previous transmission control information is permitted or not (inStep S602). If the decision is made that broadcast to the same sub-netis permitted, the process advances to Step S603, in which “0x08” (i.e.,“001000”) is added to the new transmission control information. Afterthat, by performing the processing steps S604 through S607, S610 andS611, the contents of the previous transmission control informationabout transmission to different sub-nets are set to be the transmissioncontrol information about transmission to the same sub-net. On the otherhand, if the decision is made in Step S602 that broadcast to differentsub-nets is prohibited, then the process advances to Step S608, in whichthe transmission control information rewriting section 107 determineswhether or not multicast to different sub-nets is permitted. If theanswer is NO, then the process ends, because unicast to the same sub-netshould be prohibited, no matter whether unicast to different sub-nets ispermitted or not as per the previous transmission control information.On the other hand, if the answer to the query of the processing stepS608 is YES, then the series of processing steps S609 through S611 arecarried out and the contents of the previous transmission controlinformation about transmission to different sub-nets are set to be thetransmission control information about transmission to the same sub-net.

Hereinafter, some specific examples of the content transmittingoperation by the content transmitter 101 of this embodiment will bedescribed along the time axis.

Example 1

It will be described how the content transmitter 101 operates in asituation where the transmission control information of the contentstored in the external storage device 102 is “0x20”, the IP address andsub-net mask of the content transmitter 101 are“192.168.0.1/255.255.255.0”, and the IP address of the contentdestination provided by the destination information obtaining section106 is “192.168.0.2”.

First of all, the transmission control information obtaining section 104reads the content from the external storage device 102, gets thetransmission control information of that content, and outputs it to thetransmission decision section 105 and the transmission controlinformation rewriting section 107. Meanwhile, the destinationinformation obtaining section 106 outputs the destination IP addressthat has been entered externally to the transmission decision section105 and the transmission control information rewriting section 107.

Next, the transmission decision section 105 determines, based on thetransmission control information, the content transmitter's (101) IPaddress and sub-net mask that have been provided by the transmissioncontrol information obtaining section 104 and the destination IP addressprovided by the destination information obtaining section 106, whetherthe content may be transmitted or not. In this case, since the IPaddress and sub-net mask of the content transmitter 101 are“192.168.0.1/255.255.255.0” and the destination IP address is“192.168.0.2”, the content transmitter 101 and the content destinationbelong to the same sub-net. Also, since the transmission controlinformation of the content that has been read out is “0x20”, thatcontent may be unicast to the same sub-net. That is why the transmissiondecision section 105 outputs that content without outputting atransmission refusal signal through the output terminal 108. Based onthe IP address and sub-net mask of the content transmitter 101 and thedestination IP address provided by the destination information obtainingsection 106, the transmission control information rewriting section 107decides that the content transmitter 101 and the content destinationbelong to the same sub-net, rewrites the transmission controlinformation of the content provided by the transmission decision section105 into “0x00” following the procedure shown in FIG. 8, and outputs thecontent through the output terminal 103.

Example 2

Next, it will be described how the content transmitter 101 operates in asituation where the transmission control information of the contentstored in the external storage device 102 is “0x3f”, the IP address andsub-net mask of the content transmitter 101 are“192.168.0.1/255.255.255.0”, and the IP address of the contentdestination provided by the destination information obtaining section106 is “192.168.0.255” that is the broadcast address to the same sub-netas the one that the content transmitter 101 belongs to.

First of all, the transmission control information obtaining section 104reads the content from the external storage device 102, gets thetransmission control information of that content, and outputs it to thetransmission decision section 105 and the transmission controlinformation rewriting section 107. Meanwhile, the destinationinformation obtaining section 106 outputs the destination IP addressthat has been entered externally to the transmission decision section105 and the transmission control information rewriting section 107.

Next, the transmission decision section 105 determines, based on thetransmission control information, the content transmitter's (101) IPaddress and sub-net mask that have been provided by the transmissioncontrol information obtaining section 104 and the destination IP addressprovided by the destination information obtaining section 106, whetherthe content may be transmitted or not. In this case, since the IPaddress and sub-net mask of the content transmitter 101 are“192.168.0.1/255.255.255.0” and the destination IP address is“192.168.0.255” that is the broadcast address to the same sub-net, thecontent transmitter 101 and the content destination belong to the samesub-net. Also, since the transmission control information of the contentthat has been read out is “0x3f”, the content that has been read may betransmitted in any case. That is why the transmission decision section105 outputs that content without outputting a transmission refusalsignal through the output terminal 108. Based on the IP address andsub-net mask of the content transmitter 101 and the destination IPaddress provided by the destination information obtaining section 106,the transmission control information rewriting section 107 decides thatthe content transmitter 101 and the content destination belong todifferent sub-nets, and outputs the content through the output terminal103 without rewriting the transmission control information of thecontent provided by the transmission decision section 105 following theprocedure shown in FIG. 9.

Example 3

It will be described how the content transmitter 101 operates in asituation where the transmission control information of the contentstored in the external storage device 102 is “0x00”, the IP address andsub-net mask of the content transmitter 101 are“192.168.0.1/255.255.255.0”, and the IP address of the contentdestination provided by the destination information obtaining section106 is “192.168.1.1”.

First of all, the transmission control information obtaining section 104reads the content from the external storage device 102, gets thetransmission control information of that content, and outputs it to thetransmission decision section 105 and the transmission controlinformation rewriting section 107. Meanwhile, the destinationinformation obtaining section 106 outputs the destination IP addressthat has been entered externally to the transmission decision section105 and the transmission control information rewriting section 107.

Next, the transmission decision section 105 determines, based on thetransmission control information, the content transmitter's (101) IPaddress and sub-net mask that have been provided by the transmissioncontrol information obtaining section 104 and the destination IP addressprovided by the destination information obtaining section 106, whetherthe content may be transmitted or not. In this case, since the IPaddress and sub-net mask of the content transmitter 101 are“192.168.0.1/255.255.255.0” and the destination IP address is“192.168.1.1”, the content transmitter 101 and the content destinationbelong to different sub-nets. Also, since the transmission controlinformation of the content that has been read out is “0x00”, thatcontent may never be transmitted. That is why the transmission decisionsection 105 outputs a transmission refusal signal through the outputterminal 108.

Example 4

Finally, it will be described how the content transmitter 101 operatesin a situation where the transmission control information of the contentstored in the external storage device 102 is “0x3e”, the IP address andsub-net mask of the content transmitter 101 are“192.168.0.1/255.255.255.0”, and the IP address of the contentdestination provided by the destination information obtaining section106 is “224.1.1.1” that is a multicast address of a different sub-netfrom that of the content transmitter 101.

First of all, the transmission control information obtaining section 104reads the content from the external storage device 102, gets thetransmission control information of that content, and outputs it to thetransmission decision section 105 and the transmission controlinformation rewriting section 107. Meanwhile, the destinationinformation obtaining section 106 outputs the destination IP addressthat has been entered externally to the transmission decision section105 and the transmission control information rewriting section 107.

Next, the transmission decision section 105 determines, based on thetransmission control information, the content transmitter's (101) IPaddress and sub-net mask that have been provided by the transmissioncontrol information obtaining section 104 and the destination IP addressprovided by the destination information obtaining section 106, whetherthe content may be transmitted or not. In this case, since the IPaddress and sub-net mask of the content transmitter 101 are“192.168.0.1/255.255.255.0” and the destination IP address is“224.1.1.1” that is a multicast address of a different sub-net, thecontent transmitter 101 and the content destination belong to differentsub-nets. Also, since the transmission control information of thecontent that has been read out is “0x3e”, the content that has been readmay be multicast to different sub-nets. That is why the transmissiondecision section 105 outputs that content without outputting atransmission refusal signal through the output terminal 108. Based onthe IP address and sub-net mask of the content transmitter 101 and thedestination IP address provided by the destination information obtainingsection 106, the transmission control information rewriting section 107decides that the content transmitter 101 and the content destinationbelong to different sub-nets, rewrites the transmission controlinformation of the content provided by the transmission decision section105 into “0x30” following the procedure shown in FIG. 9, and outputs thecontent through the output terminal 103.

1-3. Effects

As described above, the content transmitter 101 includes: an inputsection 114 which obtains transmission control information(corresponding to a first kind of information) and destination IPaddress (corresponding to a second kind of information) which areincluded in the content; a control section 110 which determines, byreference to the transmission control information and the destination IPaddress, whether or not to transmit the content, rewrites thetransmission control information according to the destination if thecontent should be transmitted, and outputs the content; and an outputsection 112 which outputs the content including the transmission controlinformation that has been rewritten. As a result, content cantransmitted safely and securely without permitting secondarytransmission of the content more than necessarily.

The transmission control information of this embodiment includesinformation indicating whether or not transmission of the content ispermitted in a situation where the destination and the contenttransmitter 101 itself belong to the same sub-net and in a situationwhere the destination and the content transmitter 101 itself belong totwo different sub-nets. Thus, the transmission control information canbe rewritten flexibly according to the sub-net of the destination.

Particularly, the transmission control information of this embodiment isa piece of information indicating whether or not transmission of thecontent is permitted depending on whether the destination and thecontent transmitter 101 belong to the same sub-net or not and on whichof unicast, multicast and broadcast should be adopted as thetransmission method. And the control section 110 determines, based onthe IP address of the destination, whether the destination and thecontent transmitter 101 belong to the same sub-net or not and which ofunicast, multicast and broadcast should be adopted as the transmissionmethod, thereby deciding whether the content may be transmitted or not.As a result, the transmission control can be carried out flexiblyaccording to each combination of destination sub-net and transmissionmethod, and communications can get done more safely and securely.

Other Embodiments

Although Embodiment 1 has been described herein as just an example ofthe present disclosure, various modifications, replacements, additionsor omissions can be readily made on that embodiment as needed and thepresent disclosure is intended to cover all of those variations. Also, anew embodiment can also be created by combining respective elements thathave been described for that embodiment disclosed herein.

Thus, some of those various other embodiments will be described as anexample.

In the first embodiment described above, the transmission control policyfollowing the procedures shown in FIGS. 8 and 9 is supposed to beadopted. However, this is only an example. Rather the transmissioncontrol policy may be defined arbitrarily.

Also, even though the transmission control information is supposed to bea six-bit value according to the first embodiment described above, thisis just an example, too. For example, the casting methods (transmissionmethods) available may consist of only unicast and broadcast or thenetwork types may be limited to the same sub-net. In that case, thetransmission control information is represented as a value of less thansix bits. In any case, the transmission control information has only toinclude information indicating whether or not transmission is permittedwhen the transmission method is at least one of unicast, multicast andbroadcast.

Furthermore, the content transmitter 101 is not necessarily configuredto make communications in accordance with the TCP/IP protocol. If thecontent transmitter 101 makes communications in accordance with anyother communication protocol, addresses other than IP addresses will beused as the destination information (corresponding to the second kind ofinformation). For example, in a network that uses a telephone line, agiven network may be identified by the local code of the phone number.Even in such a network, the technique of the present disclosure is alsoapplicable to controlling FAX transmission, for example.

Furthermore, even though the content is supposed to include videoaccording to the first embodiment described above, this is only anexample, too. The technique of the present disclosure is also applicableto transmitting any other kind of content, of which the transmissionshould be controlled (such as a confidential document). Moreover, thetechnique of the present disclosure is applicable to communicating notonly between departments in the same TV station but also departments inany other general company as well.

The technique of the present disclosure is also applicable to a softwareprogram that defines the processing of the embodiments described above.The operations defined by such a program may be as shown in FIGS. 6, 7,8 and 9, for example. Such a program may be not only distributed bybeing stored on a removable storage medium but also downloaded throughtelecommunications lines. The various kinds of operations that have beendescribed for the embodiments can get done by making a processor builtin an apparatus execute such a program.

Various embodiments of the present disclosure have been described byproviding the accompanying drawings, and a detailed description for thatpurpose.

That is why the elements illustrated on those drawings and/or mentionedin the foregoing description include not only essential elements thatneed to be used to overcome the problems described above but also otherinessential elements that do not have to be used to overcome thoseproblems but are just mentioned or illustrated to give an example of thepresent disclosure. Therefore, please do not make a superficial decisionthat those inessential additional elements are indispensable ones simplybecause they are illustrated or mentioned on the drawings or thedescription.

Also, the embodiments disclosed herein are just an example of thepresent disclosure, and therefore, can be subjected to variousmodifications, replacements, additions or omissions as long as thosevariations fall within the scope of the present disclosure as defined bythe appended claims and can be called equivalents.

According to the technique of the present disclosure, when content isgoing to be transmitted over a network, the transmission control policyof the source is also applicable to the destination, thus avoidingsecondary transmission to unexpected devices. Thus, the technique of thepresent disclosure can be used in various applications that requiretransmission control of content.

While the present invention has been described with respect to preferredembodiments thereof, it will be apparent to those skilled in the artthat the disclosed invention may be modified in numerous ways and mayassume many embodiments other than those specifically described above.Accordingly, it is intended by the appended claims to cover allmodifications of the invention that fall within the true spirit andscope of the invention.

This application is based on Japanese Patent Applications No.2012-052669 filed Mar. 9, 2012 and No. 2012-276723 filed Dec. 19, 2012,the entire contents of which are hereby incorporated by reference.

What is claimed is:
 1. A content transmitter that transmits content overa network, the content transmitter comprising: an input sectionconfigured to obtain the content, a first kind of informationindicating, based on the destination and transmission method of thecontent, whether transmission of the content is permitted or not, and asecond kind of information specifying the destination of the content; acontrol section configured to determine, by reference to the first andsecond kinds of information, whether or not to transmit the content tothe destination and rewrites the first kind of information; and anoutput section configured to output the content and the first kind ofinformation that has been rewritten, wherein: the first kind ofinformation represents a range of permitted recipients, indicating thatthe content may or may not be transmitted depending on whether or notthe destination and the content transmitter belong to the same sub-netand on which of unicast, multicast and broadcast is adopted as thetransmission method; the second kind of information is an IP address;and the control section determines, based on the IP address of thedestination, whether or not the destination and the content transmitterbelong to the same sub-net and which of unicast, multicast and broadcastis adopted as the transmission method, and, based on the IP address andthe first kind of information, decides whether or not to transmit thecontent to the destination and, when the destination and the contenttransmitter belong to the same sub-net and when the first kind ofinformation permits unicast to the same sub-net and prohibits multicastand broadcast to the same sub-net rewrites the first kind of informationso as to prohibit the transmission of the content to the same sub-net.2. The content transmitter of claim 1, wherein when the control sectiontransmits the content by broadcast, when the destination and the contenttransmitter belong to the same sub-net, and when the first kind ofinformation permits broadcast to the same sub-net, the control sectiondoes not rewrite the first kind of information.
 3. The contenttransmitter of claim 1, wherein when the control section transmits thecontent and when the destination and the content transmitter belong tothe same sub-net, the control section maintains information aboutdifferent sub-nets that is included in the first kind of information. 4.The content transmitter of claim 1, wherein when the control sectiontransmits the content, when the destination and the content transmitterbelong to two different sub-nets, and when the first kind of informationpermits unicast to different sub-nets but prohibits multicast andbroadcast to the different sub-nets, the control section rewrites thefirst kind of information so as to prohibit unicast, multicast andbroadcast to the same sub-net.
 5. The content transmitter of claim 1,wherein when the control section transmits the content and when thedestination and the content transmitter belong to two differentsub-nets, the control section rewrites the first kind of information soas to prohibit unicast, multicast and broadcast to different sub-nets.6. The content transmitter of claim 1, wherein the content and the firstkind of information are managed as a single aggregated file.
 7. Thecontent transmitter of claim 1, wherein the content includes video.
 8. Amethod for transmitting content over a network, the method comprisingthe steps of: obtaining the content and a first kind of informationindicating, based on at least one of the destination and transmissionmethod of the content, whether transmission of the content is permittedor not, wherein the first kind of information represents a range ofpermitted recipients, indicating that the content may or may not betransmitted depending on whether or not the destination and the contenttransmitter belong to the same sub-net and on which of unicast,multicast and broadcast is adopted as the transmission method; obtaininga second kind of information that is an IP address specifying thedestination of the content; determining, based on the IP address of thedestination, whether or not the destination and the content transmitterbelong to the same sub-net and which of unicast, multicast and broadcastis adopted as the transmission method; determining, based on the IPaddress and the first kind information, whether or not to transmit thecontent to the destination; rewriting, when the destination and thecontent transmitter belong to the same sub-net and the first kind ofinformation permits unicast to the same sub-net and prohibits multicastand broadcast to the same sub-net, the first kind of information so asto indicate the transmission of the content to the same sub-net isprohibited; and outputting the content and the first kind of informationthat has been rewritten.
 9. A non-transitory computer-readable mediumstoring a computer program to be executed by a computer embedded in acontent transmitter that transmits content over a network, the programcausing the computer to execute: obtaining the content and a first kindof information indicating, based on at least one of the destination andtransmission method of the content, whether transmission of the contentis permitted or not, wherein the first kind of information represents arange of permitted recipients, indicating that the content may or maynot be transmitted depending on whether or not the destination and thecontent transmitter belong to the same sub-net and on which of unicast,multicast and broadcast is adopted as the transmission method; obtaininga second kind of information that is an IP address specifying thedestination of the content; determining, based on the IP address of thedestination, whether or not the destination and the content transmitterbelong to the same sub-net and which of unicast, multicast and broadcastis adopted as the transmission method; determining, based on the IPAddress and the first kind information, whether or not to transmit thecontent to the destination; rewriting, when the destination and thecontent transmitter belong to the same sub-net and the first kind ofinformation permits unicast to the same sub-net and prohibits multicastand broadcast to the same sub-net, the transmission of the content tothe same sub-net is prohibited; and outputting the content and the firstkind of information that has been rewritten.
 10. A content transmitterthat transmits content over a network, the content transmittercomprising: an input section configured to obtain the content, a firstkind of information indicating, based on the destination andtransmission method of the content, whether transmission of the contentis permitted or not, and a second kind of information specifying thedestination of the content; a control section configured to determine,by reference to the first and second kinds of information, whether ornot to transmit the content to the destination and rewrites the firstkind of information; and an output section configured to output thecontent and the first kind of information that has been rewritten,wherein: the first kind of information represents a range of permittedrecipients, indicating that the content may or may not be transmitteddepending on whether or not the destination and the content transmitterbelong to the same sub-net and on which of unicast, multicast andbroadcast is adopted as the transmission method; the second kind ofinformation is an IP address; and the control section determines, basedon the IP address of the destination, whether or not the destination andthe content transmitter belong to the same sub-net and which of unicast,multicast and broadcast is adopted as the transmission method, and,based on the IP address and the first kind of information, decideswhether or not to transmit the content to the destination and, when thedestination and the content transmitter belong to two different sub-netsand when the first kind of information permits unicast to differentsub-nets and prohibits multicast and broadcast to the differentsub-nets, rewrites the first kind of information so as to prohibit thetransmission of the content.